Understanding
Groundwater
December 9, 2015
Speakers
Gabriele Ludwig, Almond Board (Moderator)
Graham Fogg, University of California, Davis
Gabriele Ludwig,
Almond Board
Graham Fogg,
University of California, Davis
Understanding Groundwater:
The Hidden Resource
Outline
•
Groundwater fundamentals
–
–
–
California groundwater occurrence & general background
Climate change and a new epoch of scarcity
Overdraft & negative consequences
•
•
•
•
•
•
•
–
•
Non-sustainable storage depletion
Subsidence
Surface water & ecosystem effects
Increased energy costs
Bad water intrusion from aquitards and from depth
Basin salt imbalance
Seawater intrusion
Sustainable yield
Groundwater myths
–
–
–
–
–
–
Pumping of “fossil water” is non-sustainable
Groundwater storage depletion always takes a long time to recover
Groundwater levels tell us how much groundwater storage is changing
Quality of most groundwater is degraded
Good quality groundwater today is likely to stay that way
Potential myth: climate change will decrease groundwater recharge
California
Water System
http://www.water.ca.gov/maps/allprojects.html
11
12
Snow Water Storage
Slides: Bryan Weare,
2012.
Definition: Snow-Water
Equivalent (SWE) is a common
snowpack measurement. It
measure the volume of water
contained within the snowpack
(as a measure of depth).
Figure: Mote (2006) Fig 5a:
Observed changes in 1 April
Snow-Water Equivalent over
the 1960 to 2002 period of
record from snow course
observations.
Paul Ullrich
CCWAS: Lecture 03
October 7, 2013
Graham E. Fogg, 2009
http://www.oehha.ca.gov/multimedia/epic/pdf/ClimateChangeIndicatorsApril2009.pd
15
The CA Water Quantity Problem
• 8th largest economy in the world.
• Produces 50% of nation’s fruits & vegetables
w/ irrigation.
• Depends on snow-storage and historically
well-timed snow-melt to satisfy demand.
• This system cannot function properly as the
snow pack diminishes due to warming.
The Major Stores of Water….
Snow
Mountain Groundwater
Surface Reservoirs
Alluvial Valley Groundwater (Especially Central Valley)
Available Central Valley Groundwater
Storage Volume
• 10 to 50×106 ac-ft
• CA’s 4 largest reservoirs = 13×106 ac-ft
(Shasta, Oroville, Trinity, New Melones)
Two Bank Accounts
When Account A is depleted,
uncontrolled withdrawals from
Account B occur
Surface Water
Bank
Account A
(known
balance,
inputs and
outputs)
Unknown
Groundwater
Bank
Account B
(unknown
balance,
inputs and
outputs)
The Major Stores of Water….
Snow
Mountain Groundwater
Surface Reservoirs
Alluvial Valley Groundwater (Especially Central Valley)
Groundwater and Surface Water
From CA Water Plan 2014
UC Water
Security and Sustainability
Research Initiative
http://ucwater.org
[email protected]
twitter: @ucwater
We apply three perspectives to
every project.
INFORMATION
INSTITUTIONS
Connected water
resources science &
management
INFRASTRUCTURE
Current program foci:
• Headwater
Management
• Groundwater
Management
• Water-Energy Nexus
• Intelligent Water
System
12/14/2015
23
Integrating water-resources data & information systems
Existing
data
User interfaces
Core data
Sensor
networ
ks
Custom
data
Point
data,
time
series
Well
monitorin
g
Landscape
data
Aircraft
Groundwate
r aquifer
water
balance
Satellite
Market,
demand &
energy
data
QA/QC
Spati
al
data,
time
series
Interpolate
d&
blended
spatial data
t
y
Modeled data
x
Valueadded
Policy & legal data & constraints:
water rights, diversions, ecosystems
UC Water Security and Sustainability Research Initiative
Aug 31, 2015
http://ucwater.org/
Water
decision
making
Basin-scale
water
Modeling & balance
prediction
Decision
support
Winter Fallow Irrigation
(Dr. Helen Dahlke, UCD)
Sutter Bypass, Sutter Co., 1997 flood
Climate Change and Groundwater:
Higher Flooding Risks BUT Greater Recharge??
Flooding and Groundwater Levels
Laura Chun/The Sacramento Bee
1997, 1995 Flood Events
Sacramento County, CA
27
Groundwater
Occurrence
Major Aquifers (http://nationalatlas.gov/natlas/natlasstart.asp)
Volcanics
Alluvial Valleys
Alluvial Valleys, Basin & Range
30
San Joaquin Valley Groundwater (from Faunt, 2009)
PreDevelopment
PostDevelopment
31
Groundwater
Unsaturated zone
Saturated zone
Land
surface
Water table
Surface water
Ground water
Creviced rock
Air
Water (not ground water) held by molecular attraction
Surrounds surfaces of rock particles
Gravel
Approximate level of the water table
All openings below water table
full of ground water
34
Air
Confined Aquifer Schematic (from Driscoll,
1986)
Potential energy in confined aquifer
Well
Myth: Old (1,000’s of yrs) groundwater is fossil water
that is not replenished enough to support pumping.
35
36
Groundwater Overdraft: Pumping more groundwater
than the system can sustain
Potential consequences:
•
•
•
•
•
•
•
Non-sustainable storage depletion
Subsidence
Surface water & ecosystem effects
Increased energy costs
Bad water intrusion from aquitards and from depth
Basin salt imbalance
Seawater intrusion
Groundwater Overdraft Trends,
Central Valley
38
Groundwater Overdraft: Pumping more groundwater
than the system can sustain
Potential consequences:
•
•
•
•
•
•
•
Non-sustainable storage depletion
Subsidence
Surface water & ecosystem effects
Increased energy costs
Bad water intrusion from aquitards and from depth
Basin salt imbalance
Seawater intrusion
Mining Ground Water
San Joaquin Valley, California
Approximate location of
maximum subsidence in the
United States identified by
Joe Poland (pictured)
40
Subsidence Induced Canal Damage
From http://www.rcac.org/pages/714?i=1002
Groundwater Overdraft: Pumping more
groundwater than the system can sustain
Potential consequences:
•
•
•
•
•
•
•
Non-sustainable storage depletion
Subsidence
Surface water & ecosystem effects
Increased energy costs
Bad water intrusion from aquitards and from depth
Basin salt imbalance
Seawater intrusion
44
From Alley et al. (1999)
From Faunt (2009)
45
Groundwater Overdraft: Pumping more
groundwater than the system can sustain
Potential consequences:
•
•
•
•
•
•
•
Non-sustainable storage depletion
Subsidence
Surface water & ecosystem effects
Increased energy costs
Bad water intrusion from aquitards and from depth
Basin salt imbalance
Seawater intrusion
Potential for Water Quality Degradation from Below is Clear and
Present, but Unaddressed
Woodland Area Aquifer System Network (Stephen Maples,
HYD 273)
Groundwater Overdraft: Pumping more
groundwater than the system can sustain
Potential consequences:
•
•
•
•
•
•
•
Non-sustainable storage depletion
Subsidence
Surface water & ecosystem effects
Increased energy costs
Bad water intrusion from aquitards and from depth
Basin salt imbalance
Seawater intrusion
The danger of
a hydrologic
basin losing its
outlet….
San Joaquin Valley Groundwater (from Faunt, 2009)
PreDevelopment
PostDevelopment
51
Mono Lake: Closed Basin
Groundwater Overdraft: Pumping more
groundwater than the system can sustain
Potential consequences:
•
•
•
•
•
•
•
Non-sustainable storage depletion
Subsidence
Surface water & ecosystem effects
Increased energy costs
Bad water intrusion from aquitards and from depth
Basin salt imbalance
Seawater intrusion
54
Groundwater Quality is
Degrading in Many Systems,
But Most of the Groundwater
Quality is Still Good
Age Distribution & Sustainability:
Groundwater Ages are Highly Mixed!
Historic Nitrate Trends, TLB:
Exceedance Rate
Percent of wells above natural background
Number of wells tested
Percent of wells above half nitrate MCL
Percent of wells above nitrate MCL
Year
Outline
•
Groundwater fundamentals
–
–
–
California groundwater occurrence & general background
Climate change and a new epoch of scarcity
Overdraft & negative consequences
•
•
•
•
•
•
•
–
•
Non-sustainable storage depletion
Subsidence
Surface water & ecosystem effects
Increased energy costs
Bad water intrusion from aquitards and from depth
Basin salt imbalance
Seawater intrusion
Sustainable yield
Groundwater myths
–
–
–
–
–
–
Pumping of “fossil water” is non-sustainable
Groundwater storage depletion always takes a long time to recover
Groundwater levels tell us how much groundwater storage is changing
Quality of most groundwater is degraded
Good quality groundwater today is likely to stay that way
Potential myth: climate change will decrease groundwater recharge